The etching process is an important unit process to the semiconductor manufacturing and could be classified into wet etching process and dry etching process. The traditional dry etching processes mainly proceeds by introducing and sputtering ions onto a surface of a wafer placed in an etching chamber. Another etching process is to introduce plasma to ionize gaseous reactant into reactive ions, and the reactive ions react with the surface of the wafer thus forming volatile products, which are then pumped out of the chamber, thereby achieving the etching process. The etching process is well known as a Reactive Ion Etching method to the person having ordinary skill in the art.
The Reactive Ion Etching method is widely used in metal etching processes, such as aluminum, tungsten, and other alloys, for its high selectivity and anisotropism. Typically, in the Reactive Ion Etching process, chlorides or fluorides are introduced into the etching chamber for reacting with surface films patterned by photoresist layers of the wafer to form gaseous products. Thereafter, the gaseous products are pumping out of the etching equipment through a piping system by a pump.
For economizing the space of etching equipment, the piping system is usually designed winding around the bottom regions of the etching chamber, and moreover, for various usages, tubes and pipes of the piping system would have different diameters and complicated conjunctions. Therefore, particles generated from the products of the etching process would easily accumulate on inner walls of the conjunctions of the tubes and pipes of the piping system, especially in the tiny ones. For instance, a cooling tube connected to a chuck, which supports a wafer in an etching chamber, is used to introduce cooling gas flowing through the back side of the wafer to decrease the temperature raise due to sputtering while an etching process is performed. For regulating the flow of cooling gas in the cooling tube, a cooling gas bypass tube is connected between the cooling tube and an exhaust gas tube, which is connected to the chamber for conveying exhaust gas out of it. Since the diameter of the cooling gas bypass tube is smaller than that of exhaust gas tube, the particles generated from the chamber would easily accumulate on the inner wall of the conjunction of cooling gas bypass tube and the exhaust gas tube. When the particles accumulated in the cooling gas bypass tube, the cooling gas supply could be affected thereby causing the profile of the surface of wafer to be inaccurate.
Because the tubes and pipes are encased in the etch equipment, they can only be maintained or repaired after the use of the etch equipment is stopped. Therefore, the piping system is not only easily blocked by particles, but is also hard to maintain. Thus, novel designs are needed to provide a piping system that is easy to maintain thereby improving the performance of etch equipment.